Thread cutting device for sewing machines



July 27, 1937. s. N. JAFFERIAN THREAD CUTTING DEVICE FOR SEWING MACHINES Filed May 10, 1955 3 Sheets-Sheet l July 27, 1937. s. N. JAFFERIAN THREAD CUTTING DEVICE FOR SEWING MACHINES Filed May 10, 1935 3 Sheets-Sheet 2 @WMXMMM July 27, 1937. s. N. JAFFERIAN THREAD CUTTING DEVICE FOR SEWING MACHINES Filed May 10, 1935 I5 Sheets-Sheet 5 Patented July 27, 1937 MAC HINES Sarkis N. Jafl'erian, Watertown, Mass.

Application May 10, 1935, Serial No. 20345 12 Claims.

My invention relates to sewing machines and has particular reference to thread cutting means for such machines.

An important object of the invention is to provide means for automatically cutting the upper thread, when the presser foot is raised.

A further object of the invention is to provide means for cutting the lower thread, which means is arranged beneath the bed-plate, so that it does not interfere with the usual sewing .operation.

A further object of the invention is to provide means to stop the machine when the thread take-up lever and needle are raised, so that the thread will not be withdrawn from the eye of the needle when the machine is again set into operation after the thread is cut, or the machine stopped for other purposes.

A further object of the invention is to provide thread cutting means which will save time, as well as thread, during the sewing operations.

A further object of the invention is to provide means of the above mentioned character which are simple in construction and reliable in operation.

Other objects and advantages of the invention will be apparent during the course of the following description.

In the accompanying drawings forming a part of this application, and in which like numerals are employed to designate like parts throughout the same,

Figure l is a side elevation of the conventional type of sewingmachine, showing my invention applied thereto,

Figure 2 is an end elevation oi. the sewing machine, showing my brake mechanism associated therewith,

Figure 2a is a detailed section through the sliding wedge,

Figure 3 is a perspective view of the brake mechanism,

Figure 4 is an end elevation of the machine, showing the thread cutting device associated with the presser foot, v

Figure 5 is a perspective view of the thread cutting device secured to the presser foot,

Figure 6 is a similar view of the same, showing the parts separated for the purpose of clearness, 50 Figure 6a is a side elevation of the upper thread cutting device,

Figure 7 is a plan view of the device for cutting the thread from the shuttle,

Figure 8 is a perspective view of such device.

55 Figure 9 is a similar view of the cutting device through an opening 39', in the race-way 38.

of Figure 8, the elements being separated for the purpose of clearness,

Figure 10 is a plan view similar to Figure 7, showing the cutting device shifted to the thread cutting position, 5

Figure 11 is a plan view of a blade included in a modified form of lower thread cutting device,

Figure 12 is a plan view of the lower thread cutting device,

Figure 13 is a diagrammatic view showingthe 10 association of the lower thread cutting device, needle and shuttle, before the thread cutting device is actuated, and,

Figure 14 is a similar view showing the lower thread cutting device actuated. 15 In the drawings, wherein for the purpose of illustration is shown a preferred embodiment of my invention, the numeral I5 designates a sewing machine as a whole, which may be of any con ventional type, such as the ordinary Singer 20 sewing machine, used in sewing garments. This sewing machine comprises a stock l6, arms l1, and head I8. The stock is mounted upon the usual fiat base or table I9, supported in any suitable manner. The head It carries a vertical 25 reciprocating needle bar 20, to which is attached the needle 2|, having an eye 22 for receiving the thread 23'. This thread is passed upwardly through the eye 24 of a vertically movable thread take-up lever 25, and then beneath the lever 25, which, in the present instance, is held stationary by a headed screw 27. The thread then passes through a thread tension device 28 and through guides 29 and 30, and to the spool 3|, from which it is unwound. The sewing machine 35 embodies the usual means to reciprocate the needle bar 20 and raise and lower the thread take-up lever 25. This means includes a wheel 32, having a'grooved pulley 33 for receiving a belt, not shown, employed in driving the wheel 40 32. This belt may be manually operated or power driven, as is .well known. Coacting with the needle 2| is the usual presser foot 34, secured to the lower end of a reciprocatory presser bar 35, in turn slidably mounted upon the head I8. 45 The presser foot has the usual needle receiving passage, as shown. The presser bar 35 may be raised by swinging a lever 36 upwardly, or the presser bar may be raised by swinging a knee engaging element or treadle 3i laterally. Cooperating with the needle 2|, for producing the stitch, is an oscillating shuttle 38, operating in a shuttle race-way'38' arranged beneath the bed IS. The lower thread from the bobbin passes The usual means are provided to feed the work from the operator as the stitch is formed. The

foregoing description is that of the ordinary or conventional sewing machine. The conven tional sewing machine includes upper and lower thread stitch forming mechanism which has been shown and described generally. Such mechanism may be of the type shown in Patent 1,877,757 or 1,051,998, but the invention is not restricted to any particular type of stitch forming mechanism.

One thread cutting device is mounted upon the presser foot 34, Figures 1, 4, 5, 6 and So. It is arranged upon that end of the presser foot remote from the operator. This thread cutting device includes a block 38, having apertures 40, for receiving screws or bolts 4| and 42, which also pass through apertures 43, formed in the shank 44 of the presser foot. The block 39 has a thread guiding opening, groove, or recess 45, passing through its lower end, and adapted to register with the slot or opening 46 of the presser foot. This thread guiding means extends longitudinally of the direction of the feeding of the work. The thread guiding grooves or passages 45 and 46 form one continuous passage leading into the needle receiving passage of the presser foot and extending to the exterior thereof. A stationary blade 41 has apertures 48 for receiving the screws or bolts 4| and 42. The cutting edge 49 of this blade is arranged adjacent to one side of the thread guiding opening or recess 45, as shown. Coacting with the stationary blade 41 is a swinging blade 50, having an extension 5|, apertured for pivotally receiving the upper bolt 4|. The blade 50 has a curved presser-extension 52, slidably engaging beneath the head of the lower bolt 42, this lower bolt carrying a spacing washer 53, next to the head 42. The function of the presserextension 52 is to retain the cutting edge 54 of the blade 50 close to the cutting edge 49 of the stationary blade, thus producing a proper shearing or cutting action of the thread, when the blade 58 is swung downwardly upon its pivot 4|. Pivotally connected with the outer end of the blade 50, at 55, is a link 56 extending upwardly for pivotal connection at 51, with a bracket 58, and this bracket is rigidly attached to the lower end of the head l8 by screws 59, or the like. The head l8 being stationary when the presser foot is raised, the blade 50, having its extension 5| raised while its end attached to the link 56 is held at the same elevation, such blade 58 is swung upon its pivot 55, and the cutting edge 54 of the blade is moved toward the cutting edge 49. It might be stated at this point that the distance that the cutting edge 54 is spaced from the cutting edge 49, when the presser foot 34 is in the lower-most position, is such that the cutting edge 54 will not be brought into cutting relation or engagement with the cutting edge 49, upon any slight or partial raising movement of the presser foot, but the presser foot must be moved upwardly to the end of its travel before the blade 50 is turned sufiiciently to cause the cutting edge 54 to coact with the cutting edge 49, to cut the thread between these edges. This is important as the presser foot is positioned at different elevations when working upon cloth of different thicknesses, and the cutting device will not cut the thread until the presser foot has been. moved to the uppermost position. The presser-extension 52 remains permanently under the head of the bolt 42. It might be stated at this point that when the line of stitching 51, formed in the work or garment 58, is produced and it is desired to cut the thread 23 of the needle 2|, the presser foot is raised and at the beginning of the upward movement of the presser foot the work is shifted from the operator and this pulls the thread into the thread guiding opening 45 and between the cutting edges 49 and 54,.and when the presser foot is raised to the uppermost position, these cutting edges will then cut the thread arranged between them.

A device is also provided to cut the lower thread from the oscillating shuttle, and this thread is indicated by the numeral 59, Figures 7 and 10.

The bed I9 is provided with an opening 68, having an end wall 6|, Figures 7, 8, and 10. This opening is covered by the usual removable plates 60, whereby the rotary shuttle 38 and associated elements are covered. Arranged within the opening 68, upon one side of the rotary shuttle 38, is a stationary bearing 62, held in place by a bolt or bolts 63, engaging the base l9. This bearing is at an elevation beneath the base l9, or cover plates carried thereby, and this bearing receives and holds a vertical rock shaft 64, also journalled near its lower end in a bearing 65, formed in an arm 66, which is bolted or otherwise rigidly attached to a stationary lug 61, as shown at 68. A tortional coil spring 69 surrounds the rock shaft 64 and has one end attached to the same, while the opposite end of this spring is attached to the arm 66, as shown. This spring is tensioned to turn the rock shaft 64 counter-clockwise in the direction of the arrow, Figure 8, for a purpose to be described. Connected with the lower end of the rock shaft 64 is a sprocket wheel 18 engaged by a sprocket chain 1 I, engaging a sprocket wheel 12 rigidly mounted upon a vertical shaft 13. This vertical shaft is ,iournalled in bearings 14 carried by a bracket 15, and this bracket is rigidly attached to the table top 16 or other suitable support. The shaft 13 is turned by means of a lever 11, rigidly attached thereto and this lever has a depending extension 18, in the form of a treadle or knee pressing element so that the lever 11 may be swung outwardly to the left by the left knee. When this is done, the shaft 13 is turned and this turning movement is transmitted to the rock shaft 64, which will then be turned clockwise in an opposite direction to the arrow, Figure 8, to actuate the thread cutting device carried thereby. This thread cutting mechanism comprises a lower plate or blade 19, provided at one end with a head 88, having openings 8|, formed therein for receiving screws 82 or the like, which engage within screw-threaded openings 83, formed in the top of the rock shaft 64. The plate or blade 19 is therefore rigidly attached to the upper end of the rock shaft to be turned in a horizontal plane thereby and this plate or blade operates above the oscillating shuttle 38,and beneath the cover plate or plates 60' and in no way interferes with the operation of the shuttle 38 and associated elements. The lower plate or blade 19 has its free end opposite the head 88 provided with a V-shaped recess 84, ailording sharp thread cutting edges 85. These edges converge in one direction to a point 86, at which the lower thread 59 is cut. Arranged upon the lower plate or blade 19 is a guard plate 81, and these plates are pivotally connected by a screw 88 or the like. The guard plate has its free end 89 normally covering the inner portions of the converging edges and point 86. The guard plate 81 has a stop extension or finger 98, bent downwardly to enter a recess 9| in the lower plate 19 and to engage the end wall 02, to limit the covering movement of the guard plate 81. This guard plate is swung to the covering position with respect to the lower plate 19 by means of a compressible coil spring 03, receiving extension 04 of the guard plate 81 and the extension 95 of the lower plate 19 and having its outer end attached to the extension 95 by winding the same within notches 86 or the like. The guard plate 81 also has a shifting extension 01 extending laterally beyond the same for a substantial distance and also laterally beyond the lower plate 10, as shown. The shifting extension 91 is adapted to engage the end wall 6|, as will be explained. When the rock shaft 64 is in the normal or starting position, the lower plate 18 Is shifted to the left, the end of the guard plate 81 covers the cutting point 86 of the cutting edges 85, and shifting extension 91 is spaced from wall 6|. When the rock shaft 84 is turned clockwise, the shifting extension 01 is brought into engagement with the wall GI and stops the swinging movement of the guard plate 81, while the lower plate 19 continues to move until end 88 contacts with the wall IiI. There is therefore a relative swinging movement between the guard plate 81 and the lower plate 19 with the result that end 89 uncovers the cutting point 86 of the edges 85. The thread 59 from the shuttle during the sewing operation, is guided or passes between the blades 85, but does not contact therewith, and since end 09 covers the cutting point 86, the thread 59 is not cut. The needle also operates between the cutting edges and the needle and its thread do not touch the cutting edges 85. Now when the cutting device, including the plate 19, is shifted to the right, Figure 10, the cutting point 86 is uncovered, and the thread 58 extending from the shuttle to the line of stitching, beneath the cloth, engages the cutting edges 85 at the point 86, and since this thread 59, beneath the cloth, is pulled laterally from the shuttle by the cutting device, such thread will be automatically cut by the device, without the necessity of the operator moving 0 the cloth away from him, as was done with cutting the upper thread from the needle. This lower thread 59 is held at its top by the cloth and at the bottom by the shuttle and hence is out between these two points.

In Figure 11, I have shown a modified form of cutter. This cutter comprises the same blade 10, having a recess I00 and cutting edge 85. This blade 19 is mounted upon the rock shaft 64 and is turned thereby. Arranged upon the lower blade 19 is an upper blade I02, pivoted thereto at I03, and this upper blade has a cutting edge I04 opposed to the cutting edge 85. A shifting extension I06 is provided to engage the wall 6| and the same spring arrangement is provided to normally hold the cutting edge I04 spaced from the cutting edge 85. The needle and the two threads normally operate between these cutting edges and have. no engagement therewith, but when the cutting device is shifted to the right, the blade I02 is swung upon its pivot I03 and blade I04 closes upon blade 85, and cuts the thread beneath the cloth, which is attached at its top to the cloth and at its bottom to the shuttle.

Brake mechanism is provided to stop the operation of the sewing machine, when the thread take-up lever 25 is in the uppermost position, so that this thread take-up lever cannot pull the thread from out of the eye of the needle when themachine is again started. This brake mechanism comprises a stop lug I01 rigidly secured to the periphery of the wheel 32 by a'bolt I08 or the like. The stop lug I01 is provided with a cushion I08, formed of resilient material, such as rubber, and held in place by a socket IIO, carried by the stop lug. Arranged opposite the stop lug I01 is a rebound-stop element'I I I having sides II2, slidably mounted in radial grooves II3, formed in the end faces of the rim of the wheel 32. The inner ends of the sides II2 are preferably bent inwardly slightly and are connected by a transverse element or bolt H4. The rebound stop element III is radially movable with relation to the wheel 32 and the stop element is normally projected radially outwardly by a compressible coil spring H5. The outer end of the rebound stop element is beveled, as shown at I I0. The transverse element or bolt I I4 has connection with a retractile coil spring I I1, attached to a pin II8, secured to the wheel 32. The spring II1 serves to normally tilt the stop element III upon its transverse axis, as shown.

Arranged near and beneath the wheel 32 is a vertical tubular guide I I9, formed integral with a stationary base I20, bolted or otherwise rigidly attached to the table top 16, as shown at I2I. Mounted to slide within the vertical tubular guide I I9 is a bolt I22, the upper end of which is beveled,

as shown at I23. The beveled faces I23 and III; are inclined in the same direction, as shown. The bolt I22 is projected above the tubular housing H0 by means of a horizontal sliding wedge I24, operating in a transverse recess I25. The upper face of the wedge I24 is inclined and has a longitudinally extending passage I26 and a slot I21 above the same. A head I28 is slidable within the passage I26 and has a shank I29, operating in the slot I21 and rigidly secured to the lower end of the bolt I22. It is thus seen that the sliding wedge I24 will raise or lower the bolt I22, depending upon the direction in which it is moved. Bolts I28 engage in grooves I29 and hold element I24 in place. The wedge I24 carries a pin or bolt I30, operating within curved slots I3I formed in a vertically swinging lever I32 pivoted at I33, and swung in one direction by means of a retractile coil spring I34. This lever is swung in an opposite direction to advance the wedge I24 by the downward pull upon a chain I35, which may extend to a treadle on the floor. Any other suitable means may be employed to swing the lever I32 for stopping the machine. It is thus seen that when it is desired to stop the machine,

the treadle is depressed and the lever I32 turned on its pivot so that its upper end is swung toward the tubular housing H9 and the bolt I22 is projected above this tubular housing. At the same time the current is cut off from the motor by any suitable means. The wheel 32 continues to rotate in the direction of its arrow, Figure 2, and beveled face H6 will trip over beveled face I23 and the upper end of the bolt I22 will now engage the shock absorbing block I00 of the stop lug I 01. This stop lug engages the side of the bolt and not the beveled face I23 thereof so that the rotation of the wheel in the direction of the arrow is stopped. The rebound stop element III being now located in advance of the projected bolt I22 will prevent rotation of the wheel 32 in a reverse direction. The stop lug I01 is so located upon the wheel 32 that the wheel will be stopped by the projected bolt I22 when the thread take-up lever 25 is in the raised position and also when the needle 2I is partly raised and assumes a position slightly above the presser foot. This withdraws the needle from the presence of the lower thread cutting device. Since the machine is stopped with the thread take-up lever 26 in the uppermost position, when the machine is again started, the lever 25 makes its down stroke and hence cannot pull the thread out of the eye of the needle 2|, when sewingis continued.

The operation of the invention is as follows:

The work 58 is placed upon the base I9, beneath the presser foot 34, in the usual manner, and the presser foot is then lowered to engage the work. The machine is started and the needle and the oscillating shuttle are driven to form the usual lineof stitching 51. The thread 23 from the needle 2| extends to the line of stitching 51 on top of the cloth 58, while the thread 59 from the shuttle extends from the shuttle to the stitching 51 beneath the cloth. When the required length of switching 51 has been made, the lever I32 is shifted to project the bolt I22 and the current is cut off from the motor driving the machine and the machine is stopped, with the thread take-up lever 25 in the uppermost position and the needle 2| elevated to a point slightly above the presser foot, and this presser foot is now in the, lowermost position. It is preferred to first cut the top thread 23 from the needle. To do this, the operator raises the presser foot 34 upwardly through a part of its vertical travel, by pressing against treadle 31 or by raising lever 36, and then moves the work 58 away from him, and this causes the thread 23 to enter the opening or recess 45 and pass between the cutting edges 49 and 54, and when the thread is in this position, it has been pulled to a certain extent through the needle. This having been done, the upward movement of the presser foot is continued and when the presser foot approaches or reaches its uppermost position, blade 50 will swing sufliciently upon its pivot to cause cutting edge 54 to close on cutting edge 49 and cut the top thread 23, and this cutting occurs at a point suitably spacedfrom the eye of the needle so that there is suflicient thread left whereby there is no tendency for the thread to pull out of the eye of the needle when sewing is resumed, lever 25 starting on its down stroke when, sewing is again started. The top thread being thus cut, the operator next cuts the bottom or shuttle thread 59, which is eifected by swinging the treadle I8 outwardly to the left. The plate 19 of the cutting device now swings to the right from the position shown in Figure 7, to the position shown in Figure 10. When the shifting extension 91 engages the wall 6|, guard plate 81 uncovers cutting point 86, and hence the intermediate portion of the thread 59 is now shifted laterally, the top of the thread being attached to the bottom of the work 58 and the lower end of the thread to the shuttle, and the thread is under tension and will be cut at the point 86. Particular attention is called to the fact that the point of cutting is remote from the shuttle so that there is a suitable length of thread extending from the shuttle to provide for the starting of the sewing. An advantage in cutting the lower thread last, is that when the lower thread is pulled prior to cutting, it will draw the out top thread through the fabric to the lower face of the same. Of course, if desired, the bottom thread could be cut first. The operation of the second form of the lower thread cutting device is very similar to the first form, the cutting being effected by blade I04 closing on blade 85. The movable blade is shifted by its extension engaging the wall 6|, as is obvious.

A great saving of time will be effected by the use of my invention. I have found approximately ten seconds can be saved each time, by the use of my invention in the cuttingof the thread, over the old method of cutting the same with scissors or by hand. This saving is not only effected by the quick cuttingof the thread, but by the fact that the machine is stopped in the right position and it is unnecessary to turn the wheel for adlusting the needle .prior to raising the presser foot, and further, it is not necessary to hold the end of the upper thread when starting to sew, as is customary, since the thread take-up lever 25 will start on its down stroke. In accordance with my invention, when sewing is again started, the presser foot is lowered, but it is unnecesary to touch the upper thread. The stopping of the machine when the thread take-up lever is in the uppermost position, is important, even when the thread is out by hand, as it will permit the starting of sewing without holding the upper thread, or turning the wheel to raise the needle.

The cutting devices are shown as applied to a sewing machine for working on garments or the like, but the invention is in no sense restricted to this type of sewing machine, as the cutting devices may be used in connection with various types of sewing machines. Further, I contemplate using the brake device without the upper and lower thread cutting devices, or with either of such devices, or both of them.

It is to be understood that the forms of my invention herewith shown and described, are to be taken as preferred examples of the same, and that various changes in the shape, size, and arrangement of parts may be resorted to without departing from the spirit of my invention or the scope of the subjoined claims.

Having thus described my invention, I claim:

1. In a sewing machine, a presser foot having a thread guiding passage, a thread cutting device mounted upon the presser foot and including a movable blade to be shifted across the passage to out the thread, and a link held against longitudinal movement and connected with the movable blade to actuate the blade when the presser foot is raised.

2. In a sewing machine, a presser foot having a needle receiving passage and a thread guiding means, the thread guiding means leading into the needle receiving passage and extending to the exterior of the needle receiving passage, a thread cutting device mounted upon the presser foot adjacent to the guiding means and including a stationary blade and a pivoted blade, a pressure extension carried by the pivoted blade, an element to engage the pressure extension and act upon it so that the pivoted blade is held in close relation to the stationary blade, and means to swing the pivoted blade upon its pivot.

3. In a sewing machine, a presser foot, a thread cutting device mounted upon the presser foot at the end of the presser foot remote from the operator, said thread cutting device having thread guiding means extending longitudinally of the feeding movement of the work, and means to actuate the thread cutting device.

4. In a sewing machine, a presser foot, a thread cutting device mounted upon the presser foot at the end of the presser foot remote from the operator, said thread cutting device having thread guiding means associated therewith, the guiding means being open at its bottom and extending longitudinally of the direction of feeding movement of the work, and means to automatically actuate the thread cutting device when the presser' foot is raised.

5. In a sewing machine, a presser foot, a thread cutting device mounted on that end of the presser foot remote from the operator, means forming a thread guide leading to the thread cutting device and extending longitudinally of the feeding movement of the work, and means to actuate the thread cutting device.

6. In a sewing machine, a presser foot having a needle receiving passage and a thread guiding passage, the thread guiding passage leading into the needle receiving passage and extending to the exterior of the needle receiving passage, a thread cutting device mounted upon the presser foot and arranged adjacent to the thread guiding passage to cut the thread within the thread guiding passage, and means to actuate the thread cutting device.

7. In a sewing machine, a presser foot having a needle receiving passage and a thread guiding passage, the thread guiding passage leading into the needle receiving passage and extending to the exterior of the needle receiving passage, a stationary blade carried by the presser foot adjacent to the thread guiding passage, a pivoted blade mounted upon the presser foot and coacting with the stationary blade to cut the thread in the thread guiding passage, and means to swing the pivoted blade upon its pivot. I

8. In a sewing machine, a presser foot having a needle receiving passage and a thread guiding groove which leads into the needle receiving passage and extends to the exterior thereof, the thread guiding groove having its open side arranged lowermost, and a thread cutting device connected with the presser foot to move therewith and disposed adjacent to the thread guiding groove.

9. In a sewing machine, a presser foot to be raised and lowered, a thread cutting device mounted upon the presser root and including a pivoted blade, and a link held against longitudinal movement and pivotally connected with the pivoted blade to actuate the same when the presser foot is raised.

10. In a sewing machine, a needle, a presser foot having a needle receiving passage and a thread guiding passage, the thread guiding passage leading into the needle receiving passage and extending to the exterior of the needle receiving passage, a thread take-up lever, a thread cutting device mounted upon the presser foot and arranged adjacent to the thread guiding passage to cut the thread therein, means to actuate the thread cutting device, and means to stop the machine with the thread take-up lever and the needle raised so that the thread will not be pulled from the eye of the needle when the needle again descends as the thread take-up lever will move down with it.

11. In a sewing machine, a needle, a thread take-up lever, a presser foot having a needle receiving passage and a thread guiding passage, the thread guiding passage leading into the needle receiving passage and extending to the exterior of the needle receivingpassage, a thread cutting device mounted upon the presser foot and arranged adjacent to the thread guiding passage to cut the thread therein, means to stop the machine with the thread take-up lever and the needle raised so that the thread will not pull from the point of the needle when the needle again descends as the thread take-up lever will move down with it, and means to automatically actuate the thread cutting means when the presser foot is raised.

12. In a sewing machine, a presser foot, a thread cutting device connected with the presser foot to be bodily shifted thereby, and a link held against longitudinal movement and connected with the thread cutting device to actuate the same when the presser foot is raised.-

' SARKISN. JAFFERIAN. 

